This simple C++ program illustrates the use of two-dimensional arrays. This program calculates the average of all the elements in the integer array named x. For this, the program uses two nested for loops. The outer loop with index i provides the row subscript. The nested for loops therefore accesses each element of the array and the inner loop with index j provides the column subscript.
using namespace std;
#define m 4
#define n 5
int i, j, total = 0;
// a 4x5 or  array variable...
// the outer for loop, read row by row...
for(i=0; i<m; i++)
// the inner for loop, for every row, read column by column
for(j=0; j<n; j++)
// the get the summation of the array elements.
// the display the array...
cout<<"q["<<i<<"]["<<j<<"] = "<<q[i][j]<<endl;
total=total + q[i][j];
// calculate the average, notice the simple typecast casted from int to float...
average = (float)total/(float) (m*n);
cout<<"\nThis program will calculate the average of the";
cout<<"\n4 x 5 array, which means the sum of the";
cout<<"\narray's element, divide the number of the";
cout<<"\nProcessing.... PLEASE WAIT\n";
// display the average
cout<<"Average = "<<total<<"/"<<m*n<<endl;
cout<<"\nThe Average = "<<average<<endl;